1. Technical Field of the Invention
The present invention relates to electrophoretic devices, methods for making electrophoretic devices, and electronic apparatuses.
2. Description of the Related Art
In a known electrophoretic device, an electrophoretic dispersion containing a liquid-phase dispersion medium and electrophoretic particles is enclosed between a pair of electrodes, at least one of the electrodes being transparent, and a voltage is applied between the electrodes to change the distribution state of the electrophoretic particles.
In the electrophoretic device, desired information can be displayed by controlling the amplitude, polarity, waveform, application time, frequency, etc., of the voltage applied between the electrodes. As an element for controlling the voltage applied between the electrodes, a transistor is generally used.
The electrophoretic device has display characteristics similar to printed matter because of its large viewing angle, high contrast, display memory capability, extremely low power consumption, etc.
Consequently, if the electrophoretic device is formed on a flexible substrate, it is considered to be possible to produce a display which is thin and soft like a sheet of paper and which is as easy to read as printed matter, i.e., electronic paper.
An example of the electrophoretic device is disclosed in Y. Chen et al., xe2x80x9cSID 01 Digestxe2x80x9d, pp. 157-159, 2001. The electrophoretic device has a structure in which amorphous silicon thin-film transistors are formed on a stainless steel thin sheet with a protective layer therebetween, and a plurality of microcapsules encapsulating an electrophoretic dispersion are arrayed so as to be in contact with the thin-film transistors.
However, in such an electrophoretic device, it is difficult to fabricate the thin-film transistors on the stainless steel thin sheet which is used as the flexible substrate. In addition, since the microcapsules containing the electrophoretic dispersion are arrayed so as to be in contact with the thin-film transistors, the thin-film transistors are chemically degraded.
It is an object of the present invention to provide an electrophoretic device which is easy to fabricate and in which the transistor is prevented from being degraded, a method for fabricating the electrophoretic device, and an electronic apparatus including the electrophoretic device.
The above object of the present invention is achieved by the constructions (1) to (43) of the present invention described below.
(1) An electrophoretic device includes a first substrate provided with an electrode; an electrophoretic dispersion layer containing an electrophoretic dispersion, the layer being disposed over a surface of the electrode remote from the first substrate; a transistor disposed on a surface of the first substrate remote from the electrophoretic dispersion layer, the transistor applying a voltage to the electrophoretic dispersion layer through the electrode; and a conducting part extending through the first substrate and electrically connecting the electrode and the transistor to each other.
(2) The electrophoretic device according to (1) further includes a counter electrode facing the electrode.
(3) In the electrophoretic device according to (2), the counter electrode is light transmissive.
(4) In the electrophoretic device according to either (2) or (3), the electrophoretic dispersion layer includes a portion interposed between the electrode and the counter electrode.
(5) The electrophoretic device according to any one of (2) to (4) further includes a counter substrate disposed on a surface of the counter electrode remote from the electrophoretic dispersion layer.
(6) In the electrophoretic device according to (5), the counter substrate is light transmissive.
(7) In the electrophoretic device according to any one of (1) to (6), the electrophoretic dispersion layer includes a plurality of capsules containing the electrophoretic dispersion.
(8) In the electrophoretic device according to any one of (1) to (7), the electrophoretic dispersion layer contains at least one type of electrophoretic particles.
(9) In the electrophoretic device according to any one of (1) to (7), the electrophoretic dispersion layer contains a plurality of types of electrophoretic particles having different properties.
(10) In the electrophoretic device according to (7), in the same capsule and/or different capsules, the electrophoretic dispersion contains a plurality of types of electrophoretic particles having different properties.
(11) In the electrophoretic device according to either (9) or (10), the properties include at least one of a charge property, electrophoretic mobility, and a color property.
(12) In the electrophoretic device according to any one of (1) to (11), the electrode is disposed in a recess formed in the surface of the first substrate.
(13) In the electrophoretic device according to any one of (1) to (12), the electrode and the transistor are disposed for each pixel.
(14) In the electrophoretic device according to (13), the number of electrodes and the number of transistors are the same.
(15) In the electrophoretic device according to (14), each electrode and the corresponding transistor are disposed on the first substrate at the positions offset from each other in the planar direction of the first substrate.
(16) The electrophoretic device according to either (14) or (15) further includes the same number of signal lines as that of the electrodes, and each transistor is connected between the corresponding electrode and the corresponding signal line so that a signal can be input into each electrode individually.
(17) The electrophoretic device according to either (14) or (15) further includes a plurality of signal lines and a plurality of scanning lines substantially orthogonal to the signal lines, and one of the electrodes and one of the transistors are disposed in the vicinity of each intersection between the signal lines and the scanning lines.
(18) In the electrophoretic device according to any one of (1) to (17), the first substrate has a multilayered structure.
(19) In the electrophoretic device according to (17), the first substrate has a multilayered structure, and each of the signal lines and each of the scanning lines are provided on different layers.
(20) In the electrophoretic device according to any one of (1) to (19), the first substrate is flexible.
(21) In the electrophoretic device according to any one of (1) to (20), the transistor is a thin-film transistor.
(22) In the electrophoretic device according to (21), the thin-film transistor is at least partially composed of an organic material.
(23) In the electrophoretic device according to either (21) or (22), the thin-film transistor is at least partially formed by an ink-jet process.
(24) In the electrophoretic device according to any one of (1) to (23), the transistor is in contact with the first substrate.
(25) In the electrophoretic device according to (24), the transistor is obtained by at least partially separating or detaching a semiconductor unit from a substrate that is different from the first substrate and then bonding to the surface of the first substrate.
(26) The electrophoretic device according to any one of (1) to (25) further includes a semiconductor unit which controls the transistor.
(27) In the electrophoretic device according to (26), the semiconductor unit is disposed on the same surface of the first substrate as that on which the transistor is disposed.
(28) In the electrophoretic device according to either (26) or (27), the semiconductor unit includes a shift register circuit for sending data, a latch circuit for storing data, and a voltage transducer circuit for amplifying data.
(29) A method for making an electrophoretic device includes a first step of forming an electrode on a first substrate, a second step of forming a conducting part so as to extend through the first substrate and come into contact with the electrode, a third step of forming a transistor so as to be in contact with the conducting part on the first substrate remote from the electrode, and a fourth step of forming an electrophoretic dispersion layer containing an electrophoretic dispersion on the electrode remote from the first substrate.
(30) In the method for making the electrophoretic device according to (29), in the first step, a recess is formed in the surface of the first substrate and the electrode is disposed in the recess.
(31) In the method for making the electrophoretic device according to either (29) or (30), in the third step, the transistor is formed so as to be in contact with the first substrate.
(32) In the method for making the electrophoretic device according to (31), in the third step, the transistor is obtained by at least partially separating or detaching a semiconductor unit from a substrate that is different from the first substrate and then bonding to the surface of the first substrate.
(33) In the method for making the electrophoretic device according to any one of (29) to (32), the transistor is a thin-film transistor.
(34) In the method for making the electrophoretic device according to (33), the thin-film transistor is at least partially composed of an organic material.
(35) In the method for making the electrophoretic device according to either (33) or (34), wherein the thin-film transistor is at least partially formed by an ink-jet process.
(36) In the method for making the electrophoretic device according to any one of (29) to (35), in the fourth step, the electrophoretic dispersion layer is at least partially interposed between the electrode and a counter electrode opposed thereto.
(37) In the method for making the electrophoretic device according to any one of (29) to (36), in the fourth step, the electrophoretic dispersion layer is formed by arraying a plurality of capsules containing the electrophoretic dispersion.
(38) The method for making the electrophoretic device according to any one of (29) to (37) further includes a step of forming a semiconductor unit which controls the transistor on the first substrate at the same side as that on which the transistor is disposed.
(39) In the method for making the electrophoretic device according to any one of (29) to (38), the first substrate has a multilayered structure.
(40) In the method for making the electrophoretic device according to any one of (29) to (39), the first substrate is flexible.
(41) In the method for making the electrophoretic device according to any one of (29) to (40), the electrode and the transistor are disposed for each pixel.
(42) In the method for making the electrophoretic device according to (41), the number of electrodes and the number of transistors are the same.
(43) An electronic apparatus includes the electrophoretic device according to any one of (1) to (28).